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KINETIC STUDIES AND MECHANISM OF CATALYSIS OF MALIC DEHYDROGENASE FROM DIOSCOREA ROTUNDATA TUBER
Author(s) -
NOK A.J.,
GIMBA C.E.,
KABGU J.A.,
OGBADOYL E.O.
Publication year - 1992
Publication title -
journal of food biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.507
H-Index - 47
eISSN - 1745-4514
pISSN - 0145-8884
DOI - 10.1111/j.1745-4514.1992.tb00457.x
Subject(s) - dioscorea rotundata , nad+ kinase , malate dehydrogenase , malic acid , product inhibition , malic enzyme , chemistry , mechanism (biology) , dehydrogenase , enzyme , dioscorea , catalysis , stereochemistry , biochemistry , biology , botany , non competitive inhibition , medicine , philosophy , alternative medicine , epistemology , pathology , citric acid
The kinetic mechanism of catalysis by malic dehydrogenase (EC 1.1.1.37) isolated from yam (Dioscorea rotundata) tuber has been delineated. Initial velocity studies with the enzyme in the presence and absence of products of the reaction revealed an ordered sequential mechanism. The K m values obtained from secondary plots were 0.05, 0.08, 0.48 and 2.56 mM for NADH, OAA, and NAD + and L‐malic acid, respectively. Product inhibition studies in both the forward and backward reactions support an ordered Bi‐Bi sequential mechanism. This begins with an obligatory binding of NAD + to form the first binary complex and a final release of NADH.